Water-disintegratable sheet material

ABSTRACT

COATED PAPER IS PROVIDED IN SHEET, ROLL OR OTHER PHYSICAL FORM AND SHAPE WHICH IS WATER-REPELLENT WHEN WETTED ON EITHER SIDE BUT WHICH READILY DISINTEGRATES WHEN BOTH SIDES ARE WETTED AS WHEN THE ENTIRE SHEET IS IMMERSED IN WATER. THE PAPER IS PREFERABLY OF TOILET OR FACIAL TISSUE QUALITY OR WATER-SOLUBLE OR ANY OTHER TYPE, PROVIDED IT IS NOT WETSTRENGTH GRADE, WHICH READILY DISINTEGRATES IN WATER. A WATER-SOLUBLE GRADE OF NON-WOVEN FABRIC MAY ALSO BE USED INSTEAD OF PAPER. THE PAPER IS FIRST COVERED WITH AN EXTREMELY THIN (2 TO ABOUT 5 POUNDS PER REAM) COATING WHICH DOES NOT APPRECIABLY PENETRATE INTO OR IMPREGNATE THE PAPER. THE COATING IS PREFERABLY AN EXTREMELY THIN LAYER OF POLYETHYLENE WHICH SERVES AS A HOLD-OUT COATING FOR A SUBSEQUENT WATER-REPELLENT COATING, PREFERABLY OF WAX, MODIFIED WITH ETHYL VINYL ACETATE OR SYNTHETIC RUBBERS AND SOFTENERS. BY FLASHING THE POLYETHYLENE OR OTHER POLYMER HOLD-OUT LAYER WITH HEAT PRIOR TO APPLICATION OF THE WAX COATING OR BY APPLYING THE MODIFIED WAT AT TEMPERATURES IN THE RANGE OF 185* TO 235*F. (DEPENDING ON THE SPEED OF THE WAX COATING OPERATION) THE STRETCH PROPERTIES OF THE POLYETHYLENE ARE TOTALLY ELIMINATED AND YET THE POLYETHYLENE SERVES AS A HOLD-OUT COATING FOR THE FLEXIBLE WAX LAYER AND PREVENTS IS FROM SINKING INTO THE TISSUE PAPER AND RENDERING IT WATER-INSOLUBLE AND WITH WET STRENGTH PROPERTIES. WHEN AN ADDITIONAL UNCOATED SHEET OF TISSUE PAPER IS PLACED ON TOP OF TH WAXY INSOLUBLE COATING THE RESULT IS A SHEET WHICH REPELS WATER AS WELL AS THE PASSAGE OF BACTERIA AND OTHER MICRO-ORGANISMS ON EITHER SIDE AND MANITAINS ITS STRENGTH BUT WHICH, WHEN WETTED ON BOTH SIDES, READILY DISINTEGRATES OR DISSOLVES MUCH LIKE AN UNCOATED SHEETOF TISSUE PAPER. WHEN WETTED ON ONE SIDE THE SHEET DERIVES ITS STRENGTH FROM THE BOTTOM LAYER OF PAPER WHICH IS KEPT DRY AND STRONG BY THE WATERREPELLENT COATING. THE COATING, ITSELF, WHILE FLEXIBLE AND VIRTUALLY PIN-HOLE FREE, HAS NO STRETCH PRPERTIES AND IS VERY WEAK. WHEN BOTH TOP AND BOTTOM LAYERS OF PAPER ARE WETTED (AS WHEN FLUSHED ON A TOILET) THE ENTIRE SHEET TEARS AND DISINTEGRATES READILY SINCE THERE REMAINS NOTHING TO SUPPORT THE THIN, WHEAK WATER-INSOLUBLE COATING. THE SHEET MATERIAL IS ADAPTED FOR A VARIETY OF USES IN THE HOSPITAL, SANITARY, NURSING HOME AND CONSUMER FIELDS AND MAY BE CUT OR SHAPED INTO SIZES AND CONFIGURATIONS SUITABLE FOR THE PARTICULAR INTENDED USE.

Aprll 4, 1972 D. H, E. LAUMANN WATER-DISINTEGRATABLE SHEET MATERIAL 2 Sheets-Sheet 1 Filed OC'C. 30. 1969 f M @uw M 5% y M f r sa f G f M U M n F M 5M in United States Patent 3,654,064 Patented Apr.. 4, 1972 U.S. Cl. 161-156 13 Claims ABSTRACT F THE DISCLOSURE `Coated paper is provided in sheet, roll or other physical form and shape which is water-repellent when wetted on either side but which readily disintegrates when both sides are wetted as when the entire sheet is immersed in water. The paper is preferably of toilet or facial tissue quality or water-soluble or any other type, provided it is not wetstrength grade, which readily disintegrates in water. A water-soluble grade of non-woven fabric may also be used instead of paper. The paper is first covered with an ex* tremely thin (2 to about 5 pounds per ream) coating which does not appreciably penetrate into or impregnate the paper. The coating is preferably an extremely thin layer of polyethylene which serves as a hold-out coating for a subsequent water-repellent coating, preferably of wax, modified with ethyl vinyl acetate or synthetic rubbers and softeners. By dashing the polyethylene or other polymer hold-out layer with heat prior to application of the Wax coating or by applying the modified wax at temperatures in the range of 185 to 235 F. (depending on the speed of the wax coating operation) the stretch properties 0f the polyethylene are totally eliminated and yet the polyethylene serves as a hold-out coating for the flexible wax layer and prevents it from sinking into the tissue paper and rendering it water-insoluble and with wet strength properties. When an additional uncoated sheet of tissue paper is placed on top of the waxy insoluble coating the result is a sheet which repels water as well as the passage of bacteria and other micro-organisms` on either side and maintains its strength but which, when wetted 0n both sides, readily disintegrates or dissolves much like an uncoated sheet of tissue paper. When wetted on one side the sheet derives its strength from the bottom layer of paper which is kept dry and strong by the water` repellent coating. The coating, itself, while flexible and virtually pin-hole free, has no stretch properties and is very weak. When both top and bottom layers of paper are wetted (as when flushed in a toilet) the entire sheet tears and disintegrates readily since there remains nothing to support the thin, weak water-insoluble coating. The sheet material is adapted for a variety of uses in the hospital, sanitary, nursing home and consumer `fields and may be cut or shaped into sizes and configurations suitable for the particular intended use.

This application is a continuation-in-part of my copending application Ser. No. 790,134, filed lan. 9i, 1969 and now abandoned.

This invention relates to sheet material in strip, sheet or roll form which is water-repellant when wetted on one side (or either side) but `which is readily disintegratable upon total immersion in water and which comprises a plurality of layers or coatings including a hold-out lm which is preferably composed of polyethylene, a thin, continuous water-repellant coating thereon of waxy or paraflinic nature or of the nature set forth in co-pending application Ser. No. 738,203, filed June 19, 1968 and which may also be made of a silicate, silicone, siloxane, latex or cel- CFI lulose derivative. Modified wax is preferred as in the aforesaid co-pending application, i.e., wax modified for adhesion and exibility lwith from 1% to approximately 40% ethylene vinyl acetate copolymer. While paratlin wax is preferred, other waxes such as microcrystalline, animal or vegetable, may also be used-especially where eventual breakdown, emulsication or biodegradability are required. Other copolymer polyethylenes such as ethylene ethyl acrylate and methacrylate may also be used as Wax modifiers. Butyl and polysobutylene synthetic rubbers may be substituted for the copolymer polyethylenes. 1n such case, the synthetic rubber content should range ideally from 5% to 8% The wax may be further modified by the inclusion of stearic acid or other stearates and softened by the inclusion of lanolin, petrolatum or other wax softeners. The wax itself should preferably be paraffin with a low melting range (typically 138 F. to 142 E). The paraffin wax may also simply be modified with approximately petrolatum or petroleum jelly. The additional ethyl vinyl acetate or synthetic rubber component are preferred when greater flex resistance is required.

Representative illustrative, non-limitative formulas for the secondary modified wax coating are as follows:

Parts by wt. Paratlin wax 96 Ethylene vinyl acetate copolymer polyethylene (Elvax Ethylene vinyl acetate copolymer polyethylene (Elvax 100 (3) Paraflin wax 70 Microcrystalline wax 2() Ethylene vinyl acetate copolymer polyethylene (Elvax 100 (4) Paraflin wax 60 Ethylene vinyl acetate copolymer polyethylene (Elvax 260) 30 Petrolatum l0 100 (5) Parain wax 5() Ethylene vinyl acetate copolymer polyethylene (Elvax 260) 3() Petrolatum 20 100 (6) Paraflin wax Ethylene vinyl acetate copolymer polyethylene (Elvax 260) 20 Microcrystalline wax 10 Petrolatum 2() (7) Parafiin wax 74 Butyl or polyisobutylene synthetic rubber 6 Petrolatum 20 lParts by wt. Parain wax 50 Microcrystalline wax 24 Butyl or synthetic rubber 6 Petrolatum 20 `(9) Paraffin wax 64 Butyl or polyisobutylene synthetic rubber 6 Microcrystalline wax 25 Lanolin (10) Paraflin Wax 64 Butyl or polyisobutylene synthetic rubber 8 MicrocryStalline wax 18 Lanolin 10 (11) Parafin or other Wax 75 Petrolatum or petroleum jelly 25 The melting range of all the above formulas is at least 25 F. higher than the temperature range of human feces, urine and vomit; the coating is therefore never in danger of being melted or dissolved by the heat of excreta or by the body in prolonged contact with it.

While a great variety of exible water-repellent coatings without stretch properties can be formulated, the above examples are preferred because of their compounding simplicity, economical cost, and safety in terms of skin irritation, toxicity and allergic reaction. While solvents such as toluene may be used in the above formulas t0 decrease viscosity, this practice is not required and generally should be avoided because of danger from irritation to the skin `and interference with chemical and microbiological testing of urine, feces, sputum, vomit and blood by the possibility of residual amounts of solvent remaining in the coating. These wax formulations, made without solvents, are also preferred over the numerous possible solvent-system or other coating formulations that may be substituted using other chemicals for the same reasons. Unlike latex, insoluble polyvinylalcohol and other aqueous formulations, the waxy coatings cover uniformly and present no drying problems.

A tissue paper layer of single or double-ply toilet or facial tissue quality is provided on both sides so that the sheet material and products made therefrom can be used from either side. The tissue paper layer -adheres to the underlying material.

The invention is further illustrated in the accompanying drawing wherein:

FIG. l is a perspective view of a three-layer sheet material according to the invention with a corner portion broken away to illustrate the construction;

FIG. 2 is a View similar to FIG. l, but wherein there is a tissue paper layer or coating on each side of the sheet material;

FIG. 3 is a view similar to FIG. 1, but wherein, 'as shown by the legends7 two units are in effect combined into a multi-layered sheet material having two insoluble coatings in Contact with one another, a polyethylene or other polyolein layer on each side of the insoluble coatings and a tissue paper layer as the external layer on each side of the composite material;

FIG. 4 is a plan view of a pan or basin having placed thereon a composite sheet material such as that of FIG. 5, the particular article being a bedpan;

FIG. 5 is an actual view of the composite material taken along line 5-5 of FIG. 4, and

FIGS. 6, 7 and 8 are views similar to FIG. 5 of further modified forms of the invention.

The simplest form of the invention is shown in FIG. 1 and involves the use of a paper or non-woven paper-like fabric which is readily water-disintegratable or watersoluble and which is coated with an extremely thin layer of polyethylene (approximately 2 to 5 pounds per ream of 3000 square feet) or other suitable plastics or other holdout materials which, when applied, will not sink into the paper. The hold-out polyethylene coating may be made 0f any low, medium, or high density polyethylene or copolymer (ethylene vinyl acetate or other) blend. Polypropylene and polypropylene copolymers, saran and polybutylene may also be used. The preferred means of depositing the hold-out layer is by extrusion coating. Other methods such as spraying molten polymer or depositing powdered polymer may also be used. The plastic coated paper is then reheated by hot air, infrared elements or other source of heat at temperatures exceeding approximately 300 F. for 5 to l0 seconds in order to break down and totally eliminate the stretch characteristics of the polymer coating. This coating `serves as a hold-out for the next layer. It does not serve as a water-repellent agent itself because, after flashing, it contains many tine pinholes which are subsequently filled by the modified wax top coating. The modilied waxy or other insoluble coating is then applied to the polyethylene or other plastic hold-out layer and is made as thin as possible while still being continuous and rendering the sheet free, or substantially free, of pinholes. The sheet, when wetted on its coated side, repels water and maintains physical strength comparable to or Slightly greater than the physical properties of the dry sheet of paper under the coating. When the uncoated side of the paper is wetted, however, the sheet disintegrates and tears much like a completely uncoated piece of the same paper. The insoluble coating exhibits no stretch properties of its ow-n. It does not sink into the paper and therefore does not impart wetstrength qualities to the paper. A non-woven fabric may be substituted for the paper base sheet but it, too, must bey water soluble. The non-woven material may be made of rayon, acetate, polyester or vinyon and in the dry state its lfibers may be held together chemically (as with a polyvinyl alcohol, carboxy methyl cellulose or other water soluble binder) or by mechanical means. Upon immersion in water the fibers must lreadily separate and disperse. The initial polyethylene or other polymer hold-out coat is applied and its stretch properties eliminated by heat in the same manner as outlined with the paper substrate. The secondary modified wax coating is similarly applied.

In the forms of the invention shown in FIGS. 2 and 3, the `sheet Will repel water on either side and prevent its passage through the sheet while also maintaining physical strength comparable to the dry sheet of the paper. In this case, the bottom or dry sheet of paper supports the thin, flexible, pinhole-free but otherwise weak coating. When this layer of paper is also wetted (as when the entire sheet 1s immersed in water or in water in a toilet bowl) there remains no support for the coating and it easily ruptures, tears and distintegrates along with the paper.

The sheet displays these unique properties because (1) the two-step coating is not impregnated into the paper but rather rides on top of it or, in the case of FIGS. 2 and 3, between it and (2) the coating itself, while pinhole-free and flex-resistant, is actually very weak and has no stretch properties. In forming the coating, polyethylene or other plastic material such as polypropylene, polybutylene or Saran is used as a base hold-out coat for the subsequent modied wax waterproof layer. This is necessary to prevent the paper or non-woven fabric from becoming saturated with the wax and thereby resulting in an insoluble or Wet-strength material. The polyethylene hold-out coating, itself, however, is treated to prevent it from exhibiting the usual stretching physical properties typical of even the thinnest coatings of polyethylene, polypropylene or other polymers. This is achieved by ashing the polyethylene coated paper for approximately tive to ten seconds at temperatures in excess of 300 F. Following flashing, the polyethylene coating no longer displays any of the usual stretching characteristics typical of even the thinnest ilms of polyethylene, polypropylene, polybutylene or saranxln order to achieve this breakdown of the stretch properties, the polyethylene must be applied in a coat no heavier than approximately 5 pounds per ream of 30G() square feet. When a paraliin wax, modified for flexibility according to the aforementioned formulas, is added in a hot melt coating operation, the prior polyethylene coating prevents the wax from impregnating the paper and achieves a flexible, pinhole-free `water-repellent surface which, at the same time, has very little Strength and tear resistance. The dry paper layers on either side of the coating provide the `support necessary for the sheet to withstand weights of up to several pounds. When the bottom sheet is wetted, however, there remains no support for the film and it ruptures in numerous tears 'and pieces and is readily flushable in a toilet. By heating the modified wax to approximately 185 F. to 235 F., depending on the speed of the coating operation, the heat of the wax alone will break down the stretch characteristics of the polyethylene as it is applied by the coater while yet being held out from impregnating the paper by it. At temperatures lower than 185 F. the stretch properties of the polymer hold-out coat will not be eliminated and the sheet, while water-repellent, Will resist tearing much like a sheet of plastic film. At temperatures in excess of 235 F., yand at coating speeds of less than 120 feet per minute, the wax will impregnate the paper by melting through the polyethylene coat. If a water-repellent coating other than hot melt is to be applied as from a solvent or aqueous system or where temperatures of approximately 185 F. to 235 F. are not to be attained, prior lflashing is necessary. The wax or other insoluble coating (such as nitrocellulose or other cellulose derivatives, lacquers, Silicones, latexes, etc.) lls the pinholes resulting from flashing in the polyethylene hold-out coating but does not impregnate the paper suiciently to form a wetstrength or Water-insoluble sheet. The entire coated sheet is very thin and of the order of thickness set forth in the aforesaid co-pending application; namely, approximately 3,/100 of an inch or less.

In the form of the invention shown in FIG. 2, there is an additional layer of uncoated tissue paper on the coated layer so that the sheet material of FIG. 2 has a tissue paper layer on each side, thereby making the material utilizable from either :side in contrast to the form of the invention shown in FIG. 1.

In FIG. 3 there is illustrated a further form of the invention wherein greater thickness and/or somewhat greater strength and resistance are required and it will be observed that in this further modified sheet material according to the invention there are in effect two threecomponent units made up and assembled in contact with one another. This unit can be made by assembling two three-component units as indicated or could be made by forming and adhering the successive layers shown.

IIn FIGS. 4 and 5 there is shown a bed-pan of conventional nature in broken lines and designated B and disposed thereover is that form of the present invention appearing in FIG. 5 wherein in sequence from top to bottom there are layers of tissue paper or water soluble nonwoven material, polyethylene wax and then an inverted set of the same materials but of smaller area. Each of the layers of material are individually the same as layers already described with reference to forms of the invention shown in FIGS. 1, 2 and 3 and since the materials are the same, it is unnecessary to specify the nature of these layers again. It will be seen by comparing FIGS. 4 and 5 that the 3-layer unit of larger area A extends beyond the basin or pan B on all sides whereas the 3layer unit of lesser area C just covers the receiving opening of the basin or pan so that when excretions are disposed thereon the full benets of the invention are obtained without the comits posite material being drawn into the basin or pan and rendered inconvenient of access.

In the further modified form of the invention shown in FIG. 6 there are three 3-layer units wherein the uppermost unit illustrated is the same :as A of FIG. 5 and the intermediate unit is the same as C of FIG. 5, but there is an additional unit with the wax layer uppermost and it will be further seen that the second and third units are the same size or area, whereas the uppermost unit is of considerably larger area. A further variation of this concept is shown in FIG. 7 wherein there are also three 3- layer units but each of which is of ditferent size or area. For example the uppermost unit is the same as the unit A of FIG. 5, the intermediate unit is the same as unit C of FIG. 5, but the lowermost unit is intermediate in size or area, being smaller than the uppermost unit but larger than the intermediate unit. The materials of all the layers are the same as described above but the modification of FIG. 7 provides a little more strength and duration of time before disintegration when in contact with water or other liquids or moisture and furthermore is useful in connection with a pan or basin of the nature of that shown in FIG. 4 to provide greater coverage of the bottom of the pan or basin. The further form of the invention shown in FIG. 8 is the same as FIG. 5 except for the inversion of the lower 3-layer unit of smaller area because it is sometimes found that it is desirable and advantageous to have a wax or waxy layer in contact with the bottom of the basin or pan rather than a watersoluble or `water-disintegratable layer as is the case in FIG. 5.

It will thus be appreciated that sheet material in accordance with this invention is versatile in that it can be made up of different combinations of substances or coatings and has great tiexibility with little or no tendency to crack due to freezing, brittleness or drying out. Furthermore, the sheet material is of such character that when it comes in Contact with Water as, for example, that in a toilet or other disposal system, the tissue paper or water-soluble non-woven outer layers readily disintegrate thereby making the water-insoluble Coating unable to retain its integrity so that the insoluble coating breaks up into a considerable number of pieces or fragments without the dry strength support of the water-disintegratable substrate. The tissue paper readily fragments and disintegrates also and hence the Whole unit is readily disposable regardless of the number of layers of coatings involved. In addition, the variety of combinations of layers, coatings and sizes and arrangements of sheets renders the invention unusually versatile.

The sheet material of the present invention is primarily intended to be manufactured and sold in the form of large sheets or rolls or long strips which, for example, can have a width up to 72 inches or more if made on conventional equipment used by paper companies. Ultimately it is intended to cut the sheet material into suitable sizes `and shapes to be employed in connection with hospital equipment such as ushable liners for bedpans and emesis basins wherein the pre-cut sheet material is used in the manner described in my aforesaid co-pending application, or liners for tlushable disposable diapers and may be either cut into square sheets of 2() inches in length on each side as an example or into any other sizes and shapes whether such be rectangular, polygonal, circular or striplike. The material is readily cut either by available cutters or by knives or scissors so that, for instance, a hospital, nursing home or clinic could purchase the sheet material of the invention in relatively large amounts or in rolls and then cut therefrom, as needed, the shapes wanted, but preferably the sheet material is pre-cut into a few different sizes and shapes for convenience. It Will also be appreciated that the sheet material could be used as toilet tlushable and disintegratable bacteria-proof toilet seat liners or covers, pet liners for pets to urinate and defecate on with none of the waste matter soaking through to rugs, etc., for disposable bibs, as a water-repellent disposable diaper liner, emesis basin liner, sanitary napkin liner, and for any other application where an article must be water-repellent and germ-repellent and strong yet should ideally be able to be flushed down a toilet without fear that it will clog the toilet or sewer because it will not disintegrate or break up in the sewage pipes and system. It is also to be understood that each of the forms of the invention can have a border of tissue paper or watersoluble non-'woven material extending beyond the edges of the cut sheets, rolls or other shapes either on two-opposite sides, on a single side or on all four sides as to finished liners and the like, thereby providing extra material for holding or -grasping the articles, for handling or manipulating them or for application to larger than average or typical areas, bedpans, basins, diapers, toilet seats, etc.

What is claimed is:

1. A flushably disposable sheet material which when wet from only one side maintains strength and water repellency but which is disintegratable when totally immersed, comprising (a) two plies of paper of toilet or facial tissue quality or non-woven fabric characterized by being watersoluble or water-disintegratable,

(b) a two layer coating on at least one of the plies, the coating being on that side of the ply facing the other ply and comprising (1) as the first layer, a non-penetrating holdout film of a polymer substantially free of stretch properties, said film being of a thickness not exceeding 5 pounds per ream and (2) as the second layer, a thin but continuous waxy coating over the film of polymer, said waxy coating comprising paraffin, microcrystalline animal wax or microcrystalline vegetable wax, alone or modified with synthetic rubber, ethylene vinyl acetate copolymer, lanolin or petrolatum.

2. A ilushably disposable sheet material according to claim 1 wherein the two plies are paper of toilet or facial tissue quality.

3. A ilushably disposable sheet material according to claim 1 wherein the polymer of the holdout film is polyethylene, polypropylene, polybutylene, Saran or a copolymer thereof with vinyl acetate.

4. A flushable disposable sheet material according to claim 1 wherein the polymer of the hold-out film is polyethylene.

5. A flushably disposable sheet material according to claim 1 wherein the waxy coating is parain modified with CII from 1% to about 40% of ethylene vinyl acetate copolymer.

6. A flushably disposable sheet material according to claim 1 wherein the two plies of paper are of toilet or facial quality; the polymer of the hold-out film is polyethylene and the waxy coating is paraffin modified with from 1% to about 40% of ethylene vinyl acetate c0- polymer.

7. A flushably disposable sheet material according to claim 6 wherein the two layer coating as therein defined is on the side of each ply facing the other ply.

8. A ushably disposable sheet material according to claim 1 wherein the two layer coating as therein dened is on the side of each ply facing the other ply.

9. A flushably disposable sheet material according to claim 8 characterized in having a third ply of paper or non-woven fabric bearing a two layer coating as therein defined on the side facing one of the non-coated sides of the first two plies.

10. A ushably disposable sheet material according to claim 1, one ply of which having the two layer coating on the side facing the other ply and the second ply of which having a like coating on the side not facing the first ply.

11. AS a new article of commerce, flushably disposable sheet material according to claim 1 in the form of a roll.

12. Pre-cut shaped articles of flushably disposable articles according to claim 1.

13. A flushably disposable sheet material according to claim 1 wherein one ply is of a different area or shape than the second ply.

References Cited UNITED STATES PATENTS 2,649,859 8/1953 Hermanson et al. 12S-287 2,896,626 7/1959 Voigtman 128-287 3,070,095 12/1962 Torr 128-284 '3,075,864 l/l963 Anderson ll-235 3,263,241 8/1966 Saulson 4-112 3,294,722 12/1966 Apikos et al. 161--235 3,378,424 4/1968 Sawyer 161-235 HAROLD ANSHER, Primary Examiner G. W. MOXON III, Assistant Examiner U.S. Cl. X.R.

1 -112, 142; 117-76 P; 12s-156,284,161-165, 235, 25o -53 

